Sunspot drawings made by Galileo Galilei in 1612 are used to derive the law of differential rotation at that time. The main interest of the work is during the...
The solar rotation rate at latitudes 0 deg, 15 deg and 30 deg has been inferred by averaging the results of 120 regions of 15 degx15 deg, which have been...
Spectral Line Selection for HMI: A Comparison of Fe I 6173 Å and Ni I 6768 Å
We present a study of two spectral lines, Fe I 6173 Å and Ni I 6768 Å, that were candidates to be used in the Helioseismic and Magnetic Imager (HMI) for...
Spectro-Polarimetric Observations and Non-Lte Modeling of Ellerman Bombs
Ellerman bombs are bright emission features observed in the wings of Hα, usually in the vicinity of magnetic concentrations. Here we show that they can also be...
Spectroscopy at the Solar Limb: II. Are Spicules Heated to Coronal Temperatures?
Spicules of the so-called type II were suggested to be relevant for coronal heating because of their ubiquity on the solar surface and their eventual extension...
Spinor: Visible and Infrared Spectro-Polarimetry at the National Solar Observatory
The Spectro-Polarimeter for Infrared and Optical Regions (SPINOR) is a new spectro-polarimeter that will serve as a facility instrument for the Dunn Solar...
Inversion techniques of the radiative transfer equation for polarized light are presented as one of the best current procedures to infer the vector magnetic...